From a6642b3ae060976b42830b7dc8f29ec190ab05e4 Mon Sep 17 00:00:00 2001
From: Michael Paquier
Date: Tue, 8 Sep 2020 10:09:22 +0900
Subject: Add support for partitioned tables and indexes in REINDEX

Until now, REINDEX was not able to work with partitioned tables and
indexes, forcing users to reindex partitions one by one.  This extends
REINDEX INDEX and REINDEX TABLE so as they can accept a partitioned
index and table in input, respectively, to reindex all the partitions
assigned to them with physical storage (foreign tables, partitioned
tables and indexes are then discarded).

This shares some logic with schema and database REINDEX as each
partition gets processed in its own transaction after building a list of
relations to work on.  This choice has the advantage to minimize the
number of invalid indexes to one partition with REINDEX CONCURRENTLY in
the event a cancellation or failure in-flight, as the only indexes
handled at once in a single REINDEX CONCURRENTLY loop are the ones from
the partition being working on.

Isolation tests are added to emulate some cases I bumped into while
developing this feature, particularly with the concurrent drop of a
leaf partition reindexed.  However, this is rather limited as LOCK would
cause REINDEX to block in the first transaction building the list of
partitions.

Per its multi-transaction nature, this new flavor cannot run in a
transaction block, similarly to REINDEX SCHEMA, SYSTEM and DATABASE.

Author: Justin Pryzby, Michael Paquier
Reviewed-by: Anastasia Lubennikova
Discussion: https://postgr.es/m/db12e897-73ff-467e-94cb-4af03705435f.adger.lj@alibaba-inc.com
---
 doc/src/sgml/ref/reindex.sgml | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/ref/reindex.sgml b/doc/src/sgml/ref/reindex.sgml
index c16f223e4ed..33af4ae02a1 100644
--- a/doc/src/sgml/ref/reindex.sgml
+++ b/doc/src/sgml/ref/reindex.sgml
@@ -88,7 +88,9 @@ REINDEX [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] { IN
     <term><literal>INDEX</literal></term>
     <listitem>
      <para>
-      Recreate the specified index.
+      Recreate the specified index. This form of <command>REINDEX</command>
+      cannot be executed inside a transaction block when used with a
+      partitioned index.
      </para>
     </listitem>
    </varlistentry>
@@ -99,6 +101,8 @@ REINDEX [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] { IN
      <para>
       Recreate all indexes of the specified table.  If the table has a
       secondary <quote>TOAST</quote> table, that is reindexed as well.
+      This form of <command>REINDEX</command> cannot be executed inside a
+      transaction block when used with a partitioned table.
      </para>
     </listitem>
    </varlistentry>
@@ -259,8 +263,11 @@ REINDEX [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] { IN
   </para>
 
   <para>
-   Reindexing partitioned tables or partitioned indexes is not supported.
-   Each individual partition can be reindexed separately instead.
+   Reindexing partitioned indexes or partitioned tables is supported
+   with <command>REINDEX INDEX</command> or <command>REINDEX TABLE</command>,
+   respectively. Each partition of the specified partitioned relation is
+   reindexed in a separate transaction. Those commands cannot be used inside
+   a transaction block when working on a partitioned table or index.
   </para>
 
   <refsect2 id="sql-reindex-concurrently" xreflabel="Rebuilding Indexes Concurrently">
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